Variable-voltage transformer.



No. 895,914. PATENTED AUG. 11, 1908.

' M. 0. TROY.

VARIABLE VOLTAGE TRANSFORMER.

APPLIOATION IILRD 1336,22, 1905.

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I M. O. TROY.

VARIABLE VOLTAGE TRANSFORMER.

'APPLIGATION FILED DEC. 22, 1905.

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No. 895,914. v PATENTED AUG. 11, 1908.

' M. 0. TROY.

VARIABLE VOLTAGE TRANSFORMER.

APPLICATION FILED DEC. 22, 1905.

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Maw. Mac 41% WM and State of New York, have coil is s shunting the flux around t UNITED STATES PATENT OFFICE.

MATTHEW o TROY,

OF. SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

I VARIABLE-VOLTAGE 'mnnsronnnn.

Specification of Letters Patent.

Patented Aug. 1 1, 1908.

Application filed'beceinber 22, 1905. Serial No. 292,966.

To all whom-it may concern:

Be it known that I, MATTHEW O. TR'oY, a citizen of the United States; residing .at Schenectady, in the county of Schenectady invented certain new and useful Improvements in Variable-Voltage Transformers, of which the following. is a specification.

My invention relates to transformers adapted to give a wide range of secondary voltage, and consists in an the transformer described in m cation, Serial N o. 1 16,208, filed J uly 19, 1902. In that former ap lication I described a transformer in whlc the primary and secondary coils are spaced apart on the core and a portion of the core is movable to shunt the secondary coil, and thereby to vary the induced secondary voltage.

My present invention in one aspect consists in providing'means'not only for mag-' netically shunting the secondary coil, but also for varying the reluctance of the magnetic circuit passing through the secondary coil. When the magnetic shunt is removed improvement in and the device is soarranged as to give alow reluctance for the magnetic circuit passing through both primary and. secondary coils the leakage is comparatively'sm-all and the induced secondary voltage is high, as in the case of the transformer descrlbed in my former a plication; and when the secondary l iunted and the reluctance-of this ma netic circuit is made very high, prac tica ly no flux passes through the secondary coil, and consequently the induced voltage is reduced almost to zero. By varying the reluctance of the magnetic circuit of the secondary coil, as well as the magnetic circuit shunting .the secondary, I am able to et a much greater range of'jsecond'ary vo tage than isotherwise possible. I In another aspect, my invention consists in magnetically balancin the means for e secondary coil. More specifically stated, I provide two movable members, one arranged to vary the reluc'tance o'f themagnetic circuit ofv the secondary coil and the other to vary the Ifeformer appli-.

vlce. My invention further comprises certain novel arrangements of the core and coils, so as to adapt the transformer forspecial purposes.

My invention will best be reference to the accompanying drawing, in wh understood by ich Figure 1 shows a'plan view of a variable voltage transformer arranged in accordance 'with :vation of the same ;Fig. 3 shows a side eleva Fig. 4 shows an end elevation of amodition; fied t of co modification volta e polyp ase circuits.

sents a magnetic core built u clamped between the endcore 1s essentially E-shapeJ: Fig. 1, in which. the outline tions is shown indotted lines. f

my'invention; Fig. 2 shows an end eleconstruction; Figs. 5 and 6 show a modiarrangement-of coils adapted for cer- Hurposes; Figs. 7 and'8 show diagrams connections; Fig. 9 shows still another and Fig. 10 shows .a variabletransformer arranged for use on Referring first to Figs. 1 '2 and 3, A repreof laminationsates a, a. This asap ears from of t e lamina-. Primary and small effort is required for operatingthe desecondary coils P and S are mounted on the I central .leg of the E, the primary coil being at the'inner end and the secondary coil s aced a certain distance from the and C represent two vertical netic members onlopposite ondary coil S. The member B, by its moverimary .co1 'B ymovable magsidesof the sec-,

ment, varies the reluctance of a ma netic circuit for the flux of the ing the secondary coil in t in my former application.

e same manneras The member C on the other' 'ha nd, varies the reluctance of the magnetic clrcuit passing through both coils B is raised and member shown in the drawings,

P and S. Consequently when member C is lowered, 1 as the primary leakage fluxis comparatively small and the induced .seconda'ry voltage is at its maximum value. If, however, the member C is raised and the,

- member B lowered,

secondary voltage will be almost zero.

order to movethe two members B and C, I provide a'rotatableshaft D with a hand- 1d operatively connected to both memrimary-coils unt- I practically no flux-willy. ass (through the secondary coil and the in-''. uce

. through the other.

- tages.

hers in such axmanner that one member is I ously lowered. In other words, the device is magnetically balanced and requires little efiort for operation. The bearings for shaft D are mounted directly 'on one of the clam ing plates (1., which in turn is bolted to tlie other clamping late, thereby giving a very rigid mechanica construction.

In Fig. 4 I have shown a sli ht modification of the movable members. In this figure, I have shown the member C of Fig. 2 divided in the'middle and the top and bottom portions provided with right and left-hand screwthreads so that the two portions are drawn apart instead of the whole member moving in one direction. Furthermore, I have shown the laminations of the members C and C in a plane at right angles to the main core A. This arrangement is not as good electrically as that shown in Fig. 2, but it is sometimes more comvenient mechanically.

A variable-voltage transformer of the type described above is applicable wherever a wide range of voltage is ,required; as, for in stance, for testing purposes or for thawing water pipes. 'A perfectly even variation is obtained instead of the step-by-ste variation obtained by resistance contro or by varying the number of turns of one winding.

' This is especially important in testing cables or other devices possessing capacity on account of the danger of suddenly striking resonant conditions in a step-by-step control.

For certain purposes, special arrangements of coils are especially convenient and desirable. For instance, I have shown in Figs. 5 and 6 an arrangement of coils which is particularly adapted for controlling the volta e of an alternating-current load circuit. 11 this arrangement I have shown two secondary coils S and S so arranged on the core A that when the flux of the primary coil P is diverted from one secondary coil, it is passed Such an arrangement of coils may be connected as shown in Fig. 7 rIor controlling the voltage of an alternating-current load circuit. The two coils S and S are connected in series with each other and with the load circuit, but in opposition to each other with respect to their lnduced vol- By shifting the members F and F shown in Figs. 5 and 6, the voltage supplied by the secondary coils to the line in series with the line-Volta e may be controlled both in amount and in irection; Obviously, the same result is obtained if the coils S and S in Figs. 5 and 6 are primary coils and the coil,

P a secondary coil. Fig. 8 shows the connections in such a case. The two primary coils are connected in series, and in opposition with respect to voltage, in the same way that the secondary coils are connected in Fig. 7, while the secondary coil is connected directly in series with the line.

The construction shown in Figs. 5 and 6 would produce a strong horizontal pull on the cores-F and F so that in practice I prefer the arrangement shown in Fig. 9, which is electrically the equivalent of the arrangement of Figs. 5 and 6; but in which the moving members are magnetically balanced not only against each other, but with respect to horizontal pulls.

Fig. 10 showsa modification of the arrangement of Fig. 9 adapted for use on polyphase circuits. In this figure the core A is arranged with a plurality of magnetic circuits like the usual three-phase transformer, three primary coils P P and P being mounted on the several legs of the core with the secondary coils S S S S S S also mounted on the several legs of the core. Two secondary coils S S are mounted on the same leg with the primary coil P and the other coils for the other bases are similarly arranged. The movab e members 'F and F are arranged to move simultaneously but oppositely, as here tofore eX lained, and each member serves both to s unt simultaneously the secondary coils of all three phases adjacent to it, and

also to vary the reluctance of the magnetic circuits passing through the secondary coils at the opposite end of the core.

Other arrangements of coils and cores may be employed to meet varying requirements, and consequently I do not desire to limit myself to the construction and arrangement of parts here shown, but aim in the a pended claims to cover all modifications wllich are within the scope of my'invention.

- What I claim as new and desire to secure by Letters Patent of the United States, is,

1. In a variable-voltage transformer, a stationary primary coil and a stationary secondary coil, a core "adapted to afford two-magnetic circuits, one passing through both coi s and one shunting one coil, and magneticallybalanced means for varying the reluctance of each magnetic circuit.

2. In a variable-voltage transformer, a stationary primary coil and a stationary secondary coil, a core adapted to aiiord two mag netic circuits, one passing through both coils and one shunting one coil, and magneticallybalanced means for simultaneously and oppositely varying the reluctances of both magnetic circuits.

' 3. A variable-voltage transformer. comprising a core, stationary coils s aced apart on said core, and two movab e magnetic members magnetically balanced arranged to vary the reluctance respectively of a magnetic circuit passingthrough one 2} said coils and of a magnetic circuit shnntin said coil.

4. A variable-voltage transformer comcore arranged to afford a magnetic circuit shunting said coil, and

prising a core, stationary coils spaced apart on said core, two movable magnetic members magnetically balanced arranged to vary the reluctance respectively-of a magnetic circuit passing through one of said coils and of a means for simultaneously moving said members. i 'Y 5. A variable-voltage transformer com prising a core, a stationary primary coil and a stationary secondary coil spaced apart on said core, and two movable magnetic members. magnetically balancedarranged to vary the reluctances respectively of the magnetic circuit of the secondary coil and of a mag-- netic circuit shunting said coil.

-6. A variable-voltage transformer comprising acorefa stationary primary coil and a stationary secondary coil spaced apart on said core, two movable magnetic members magnetically balanced arranged to vary the reluctances respectively of the magnetic circuit'of the secondary coil and of a magnetic circuit shunting said coil, and means for simultaneously moving said members. 7. A variable-voltage tranformer comprising a core, stationary coils spaced apart on saidcore, two movable magnetic mem bers magnetically balanced arranged to vary the reluctances respectively of a magnetic circuit passing through one of said coils andof a magnetic circuit shunting said coil, and a rotatable shaftoperatively connected with both members. I

8. A variable-voltage transformer comprising a core, stationary coils" spaced apart on said core,'two movable magnetic mem' bers magnetically balanced arranged to vary the reluctances respectively of a ma etic cifrcuit passing through one of said 00' sand 0 rotatable shaft operatively connected with bothmembers," and a hand-wheel for rotating said shaft. l v

9. A- variable-voltage transformer comprising a core, stationary coils spaced apart on said core, two movable magnetic members magnetically balanced arranged to vary the reluctances respectively of a ma etic circuit passing through one of said 001i? and of a magnetic circuit shunting said coil, ,a rotatable shaft, and operative connections. between said shaft and bothmembers whereby said members are moved in o posite directions when said shaft is rotate 10. In a variable-voltage transformer,- aplurality -of mag netic circuits, a coil on a portion of said core. common to two magnetic circuits, two coils on two other portions .of the core each inclu ed in only one of said two magnetic circuits, and means for varying the reluctance of each of said ma netic circuits.

11. In a variab e-voltage transformer, a core arranged to afford a plurality of magmg the reluctance of each a magnetlc circuit shunting said coil, a

coils of each netic circuits, a coil on a portion of said core common to two magnetic circuits, two coils on two other portions of the core each included in only one of said two magnetic circuits, said two coils being electrically connected in series and in op osition with re spect to their voltages, and means forvaryi of saidmagnetic circuits. 7 12. In a variable-voltage transformer, a

core arrangedto afford a plurality of magnetic circuits, a coil on a portion of said core common to two' magnetic circuits, two coils on. two other portions of the core each included in only one of said two magnetic circuits, said -two coils being electricall con nected in series and in opposition with'respect to theirwoltages, and means for varying slmult-aneously and oppositely the reluctances of said two magnetic circuits.

13. In. a variable-voltage transformer for polyphase circuits, a core affording a plurals ity of magnetic circuits, a p01 hase arrangement of rimary and secon ary coils carried on, said core, and-magnetically bal anced movable magnetic members adapted by their movements to vary simultaneously the mutual induction of primary'and sec ondary coils of the several phases.

14. In. a yariable-voltage transformer for; 95 polyphase circuits,

a core aflording a plurality of magnetic circuits, a-p'olyphase :ar' rangement of primary and secondary coils on said core, and members one arranged to vary the reluctance of the magnetic circuits passin through both coils of each phase-and the other to, vary the reluctance of magnetic circuits shunting the secondary coils of the several phases 15. In a Variable VoItage transformer for polyphase circuits, a core lty of magneticcircuits, a p01 hase arrangement of primary and. secon ary colls on said core, two movable magnetic members one arranged to vary the reluctance of the magnetic circuits passing through both base and the other to vary the reluctance o magnetic circuits shunting the secondary coils bers.

. 16. Infa variable voltage transformerja core/, coils spaced apart on said core, and ma etically-balanced.,means adapted to 120 s t 'the'flux from one portion of said core to another- J 17. In a variable voltatge transformer, a core, primary and. secon arycoils-spaced apart on said core,i and magnetmally-bal- 125 anced means for sh nting the flux around the secondary coil. p

" 1 8. A variable volta 'e transformer-com: rising a core formed of aminations clamped etween end-plates,

two movable magnetic I affording a pluralof the several phases, and. means for slmultaneouslymovmg sald mema stationary primary netic circuit passing through and a stationary secondary coil spaced apart on said core, two movable magnetic menibers magnetically balanced arranged to var the reluctances respectively of a magboth primary and secondary coils and a magnetic circuit shunting the secondary coil, a rotatable shaft operatively connected with both members, bearings for said shaft secured to one of said endlates, and a hand-Wheel for rotat- 10 in said s aft. 4

n'witness whereof, I have hereunto set my hand this 20th day of Deceinebr, 1905.

MATTHEW O; TROY.

' Witnesses:

BENJAMIN B. HULL,

HELEN ORFORD. 

